Air mixing apparatus



March 13, 1945.

H. A. WHITESEL AIR MIXING APPARATUS Filed Jan. 26, 1944 uounnh nuuunoUuuuuu Figi.

.Inventor Hart-,g A.Whtesel Patented Mar. 13, 1945 UNITED STATES PATENTOFFICE l' I. AIR nmnllnmrrus Harry A. WhiteseL AGlen Ridge,5.,.assig-nor `to General ,Electric .Com

vNew York` pany, a 'corporation of Application .flannel-yes, 1944,.serial No. s195771 (Cl. 13S-4 2.) .My invention relates yto .airconditioning ap- I 17 Claims.

paratus and more iparticularly to apparatus for mixing lair in .astreamso that the .atmospheric conditions thereof are` uniform throughout across-section of ,the stream.

.the determination of the performance of airconditioning .apparatus itisfrequently necessary to know the average temperature o r the .averagehumidity of the air in a stream; normally, however, the .atmosphericconditions prevailingover the `.cross-section Hof a stream of air vary.widelyso .that temperature measured atone point. in` the cross-sectiondiffers from that at another point. It is desirable that a singlereadingof ..a thermometer or .humidity indicating device besuiiicient todetermine thenaverage tem- "Referring now to the drawing, Fig. 1illustrates a calorimeter `comprising a `thermally insulfated cabinet'I0 including a compartment I I iii-which is larranged `a `heat`exchanger I2 to be tested, a compartment I 3 containing` an air-circulating fan' I4, heat exchange apparatus r4'I'.i and humidifyingapparatus I6. A middle compartment 'I1 is provided :between thecompart-4 ments H and I3 and lmay contain the connections l('not'shown)`to the heatv exchange apparatus for conducting Vvheat exchangefluid tothey 'pera'ture .or humidity .of the stream. "Asingle reading maybesufficient provided the stream Pis thoroughly .mixed to render theatmospheric conditions uniform throughout the cross-sectional .area ofthe stream.` It is desirable that apparatus for `testing the`performance of an air conditioning` system be as compact .as possible;`and in order to obtain the desired ,compactnesa .it is ,oftennecessaryto provide a change in direction of. thestrearn of air. Itis an objectof my i11vention`toproyide an improved apparatus for thoroughly mixing,the air inv a .stream ,to ren- `der uniform the atmospheric 4conditionsthrough- Aout a cross-sectionofl the stream. o

` It is another object o'f my .invention Vto provide a compact andefficient apparatus for thor- .oughly mixing the air in astream torender the atmospheric conditions thereof (uniform `through- .out .a.cross-section .of thefstream and Aincluding an improved`arrangementlfor changing the direction of the stream during the airmixing operation.

Further objects and advantages of Lmy invention will become apparent asthe following deapparatus in the other compartments. Communicationbetween the compartments II and I3 is provided Vat one end'by anairmixing apparatus and at; the other end by ya similar apparatus 2I. Thecabinet 10 is, of course, provided with doors providing `access to vthe`several compartments of the -cabinet. These doorsv have not been shown4as they are not necessary to an understanding ofthe invention. vThecalorimeter o y provides anarrangement `whereby air may be circulatedover the unit I2 which is to betested and-may the'nbe returned to thecompartment `I3 where its temperature and humidity'are restored`to'ytheir values before passing over the unitIZ During the operation oithe vapparatus llustrated,`;the 'nit 4 I2 Iis supplied with heating.scription proceeds,` and `the features of novelty .which characterizemy invention will be Jpointed .out `with particularity in the claimsannexed to `and forming part of thisspecication.

`.For a .better `,understanding of my invention .reference may be `hadtothev accompanying drawing in which Fig. 1 yis a'sectional elevation viewof a calorimeter lfor testing/heat exchangeunits .-and ,including ,airmixers embodying my inven- Etion; Fig. .2. is an enlarged perspectiveview of -the ,air mixing apparatus shown in Fig.` 1 with the air v orcooling uid at `a predetermined temperature and air-is circulated`through the cabinet by operation of the fan M. `The air leaving the fanI4 passes through the -mixing device 2l andis discharged from the deviceintovthe cabinet Il, the air. in fthe stream discharged from the device2| being of uniform condition throughout its cross-sectional area sothat a thermometer -orother Vtemperature measuring device 22 and arelativehumiditymeasuring device 23 may be placed 4atthe outlet oftheapparatus` 2| to determine the average temperature and average rela-tivehumidity ofthe airsupplied to the heat exchanger I2. After the air ispassed over the -unit I2, `it enters themixing vapparatus 20 and isdischarged therefrom into the compartment` I3, the average'temperatureand -humidity ofthe air discharged to the compartment I`3 being uniformthroughout the lcross-section of the discharge `outlet so that lathermometer or utemper- -ature measuring `device 25 and a relativehumidity `measuring-device 26 may be employed to determine the averagetemperature and Lrelative humidity of the air .as a result of itsyhavingpassed over the heat exchange unit I2. This 'air then passes overtheheat 4exchanger I5 where fitis either heated or cooled kand ,over thehumidvi-fgying apparatus I6 so that the air `returned to the fan |4 isrestored to a predetermined condition before its recirculation to thecompartment The calorimeter thus comprises an apparatus for circulatingair in a closed path under conditions such that it is supplied to theheat exchange unit to be tested at known temperature and relativehumidity and so that the performance of the heat exchange apparatus maybe measured.

The details of the construction of the air mixers 29 and 2| are shown inFig. 2. Both the mixers and 2| are of the same construction. Fig. 2 maybe considered as a view 0f the mixer 2| since its inlet and outletcorrespond in position to those of the mixer 2|. The mixer asillustrated comprises a rectangular frame work constructed of angle ironmembers 21, and is provided with an inlet over which is secured aforaminous plate or screen 28 and an outlet over which is secured asimilar screen 29, the mixer being completely closed except for theinlet and outlet. The screens 28 and 29 and the several walls of theapparatus are secured to the angle iron members 21 to form a rectangularbox-like duct structure. These screens serve to make the velocity of theair uniform over the cross-sec,- tional area at the inlet and outlet ofthe device. The mixer is divided into three compartments by solidpartitions 30 and 3|, the lower comparte ment, indicated at 32, beingthe inlet compartment, the upper compartment 33, the outletcompartment,and the intermediate compartment 34 being formed between theinlet and outlet com.. partments. The front side of the intermediatecompartment 34 is closedv by a wall 35 between the screens 28 and 29.Communication between the compartments 32 and 34 is afforded by an iopening 36 formed at the rear of the partition 30 remote from the inlet'and betweenv the partition and the side and rearwalls of the mixer.Communication between the compartment 34 and the outlet compartment 33is afforded by an opening 31 in the partition 3| between the rear walland the other side wall of the mixer. An upright baille or partitionmember 38v is provided so that it extends transversely between thepartitions 30 and 3| and prevents direct passage of air between theopenings 36 and 31, the partition 38 dividing the compartment 34 intotwo sec- 1 'z tions maintained in communication through an opening 39formed between the partition 38 and the front wall of the mixer. It willthus be evident that the air stream passing through the inlet screen 28is directed in a tortuous path l through the three compartments of themixer. A mixing apparatus of this general type but which does notprovide a reversal of the direction of the air between the inlet and theoutlet is described and claimed in my copending applicai,

tion, Serial No. 511,270. led November 22, 1943, and assigned to thesame assignee as my present invention.

I have found that by making the openings 36, 31 and 39 of across-sectional area less than onehalf of the cross-sectional area ofthe inlet 28, and preferably of the order of one-third the area of theinlet, the air stream passing through the apparatus is thoroughly mixed.This thorough mixing is further facilitated by making the compartment 34of smaller cross-section and volume than the compartments 32 and 33 sothat the air inpassing from the inlet compartment to .the compartment 34is reduced in average cross-section and is correspondingly increased inaverage cross-section on passing into the outlet compartment 33. Theinlets and outlets are preferably of the same cross-sectional area. Themixing apparatus is preferably rectangular in form and thecross-sections of the compartments and the openings are also preferablyrectangular, and the inlet and outlet openings between the compartmentsare also rectangular.

A'n apparatus constructed as shown in Fig. 2, when tested, providedthorough mixing of the air, as is illustrated by curves of the graph ofFig. 3. Fig. 3 represents the temperatures prevailing in eighteenpositions over the inlet and outlet of the apparatus shown in Fig. 2,the curve 40indicating thek temperatures prevailing at the inlet and acurve 4| the temperatures at corresponding positions at the outlet. Eachcurve is broken into vthree parts connected by ,dotted lines and eachpart comprises six temperature readings in top, middle and bottom rows,respectively, of the inlet and outlet openings. Itis readily apparentthat the temperaturesl at the inlet, as indicated by the curve 40, varywidely Whereas the temperatures over the cross-sectional area at theoutlet are substantially constant. It is readily apparent from Fig. 3that the possibility of error due to measuring the temperature at asingle point in order to determine the average temperature has beenminimized. i

The dimensions of the air mixing apparatus illustrated in Fig. 2 areselected so that no undue l pressure drop will, exist in the calorimeterand are selected in accordance with the capacity of the fan |4.

From the foregoing it is readily apparent that I have provided a simpleand easily constructed arrangement which makes it possible to mixthoroughly the stream of air passing through a duct and, furthermore, issuch that the direction of the stream of air may be reversed, thisconstruction lending itself particularly to closed circuit apparatussuch as the calorimeter illustrated.

,While I have described my invention in connection with a calorimeterfor determining the performance of heat exchange apparatus,` otherapplications will readily be vapparent to those skilled in the art. I donot, therefore, desire my invention to belimited to the particularconstruction illustrated and described, and I intend by the appendedclaims to cover all modifications which fall within the spirit and scopeof my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An apparatus for effecting thorough mixing of the air in a stream toprovide uniform atmospheric conditions throughout a cross-section of thestream comprising a duct structure having an inlet and an outlet,partitions arranged in the duct for dividing said duct into two endcompartments communicating respectively with said inlet and said outletand a third compartment between said end compartments, said partitionsbeing arranged toprovide openings between said end compartments and saidthird compartment remote from said inlet and said outlet, a baule insaid third compartment extending transversely between said partitionsfor preventing direct passage of air from' one of said openings to theother and dividing said third compartment into two sections having an`opening therebetween whereby air passingl from said inlet to of `the4air `in a stream 'less than one l1"V the-area of 'said ing `an areainlet. x

2. .An apparatus for pheric conditions throughlloutA a'cross-z-'secti'on of he stream comprising a rectangular ductstrucoutlet, a baiiiein said third compartment extending transverselybetween said partitions for preventingvdirect passage of air from one ofsaid openings to the other and dividing saidthird compartment into twosections having an openingtherebetween whereby air passing from saidinlet to said outlet is directed through said compartments in a tortuouspath, all of said openings being of substantially the same size and eachhaving an area of the order of one-third that of said inlet. V

3. An apparatus for effecting thorough mixing of the air in a stream toprovide uniform atmospheric conditions throughout a cross-section of thestream comprising a rectangular duct structure having a rectangularinlet and a rectangular outlet in the same wall thereof, partitionsarranged in the duct for dividing said duct into two rectangular endcompartments comi muncating with said inlet and said outlet and a thirdrectangular compartment between said end compartments, said partitionsbein-g arranged to provide rectangular openings between said endcompartments and said third compartment remote from said inlet and saidoutlet, a baille in said third compartment extending transverselybetween said partitions for preventing direct passage of air from one ofsaid openings to the other and dividing said third. compartment into twoSections having anopening therebetween whereby air passing from saidinlet to said outlet is directed through said compartments in a tortuouspath, all of said openings being of substantially the same size andVeach having an `area less than one-half the area of said inlet.

4. An apparatus for effecting thorough mixing of the air in a stream toprovide uniform atmospheric conditions throughout a cross-section of thestream comprising a duct structure havingv an inlet and an outlet,partitions arranged in the duct for dividing said duct into two endcompartments communicating respectively with said inlet and said outletand a thirdA compartment between said end compartments, said thirdcompartment having a volume substantially less than the volume of one ofsaid end compartments, said partitions being arranged to` provideopenings between said end compartments and said third compartment remotefrom said inlet and said outlet, a baille in said third compartmentextending transversely between said partitions for preventing directpassage of air` from one or said openings to the other and dividing saidthird compartment into two sections having an opening therebetweenwhereby air passing from'said inlet to saidv outlet is directed throughsaid compartments in a tortuous path, all of said openingsbeing ofsubstantially the same size and each i having an area less than one-halfthe area of said inlet whereby the cross-sectional area of the stream'vpassing 1through -fsaid duct .iisfreduced lo'n passing from saidinlet'to said third `compartment 4vand is `increased uponpassingffromwsaid third compartment toward said outlet. i

5. An apparatus for effecting thorough Amitrin-g of theair in a streamto provide uniform at- 'inospheric conditions throughout .across-section of 'the `stream comprisinga virectaiigula'r duct structure*having an. inlet and Yan outlet in the same side wall thereof,partitions arranged in the duct for dividing said duct into tworectangular end compartments communicating respectivei ly with saidinlet and said outlet, andfa third rectangular compartment between saidend compartments, said third compartment having a volume substantiallyless than the volume of either of said end compartments, said partitionsbeing arranged to provide rectangular openings between said endcompartments and said third compartment remote from said inlet and saidoutlet, a baille in said third compartment extending transverselybetween said partitions for preventing direct passage of air from one ofsaid openings to the other and dividing said third compartment into twosections having an opening therebetween whereby air passing from saidinlet to said` outlet is directed throughA said compartments in atortuo-us path, each of said openings having an area less than one-halfthe area of said inlet whereby the cross-sectional area of the streampassing through said-duct is reduced on passing from said inlet to saidother compartment, and is increased upon passingfrom said thirdcompartment toward said outlet.

6. An apparatus for effecting thorough mixing of the air in a stream toprovide uniform atmospheric conditions throughout a cross-section of thestream comprising a ductstructure having an inlet and an outlet,partitions arranged in the duct for dividing said duct into two endcompartments of substantially the same size communicating respectivelywith said inlet and said outlet and a third compartment between said endcompartments, said third compartment havl ing across-sectional area ofapproximately twothirds the cross-sectional area of each of said endcompartments, said partitions being arranged to provide openings betweensaid end compartments `and said third compartment remote from said inletand said outlet, a baiie in said third compartment extendingtransversely between said partitions for preventing direct passage ofair from one of said openings to the other and dividing said thirdcompartment into two sections having an opening therebetween whereby airpassing from said inlet to said outlet is directed through saidcompartments in a tortuous path, all of said openings and thecross-sectional area of each of said two sections being of substantiallythe same size and each having an area less than one-half the area ofsaid inlet whereby the crosssectionalarea of the stream passing throughsaid vduct is reduced on passing from said inlet to said thirdcompartment and is increased upon passing from said third compartmenttoward said outlet. y 7. An apparatus for eiecting thorough mixing V oi"the air in a stream to provide uniform atmospheric conditions throughouta cross-section of the stream comprising a rectangular duct structurehaving a rectangular inlet and a rectangular voutlet in the same wallthereof, said inlet andoutlet having the same cross-sectional area,partitions arranged in the duct for dividing said duct into tworectangular end compartments communicating with said inlet and saidoutlet and a l third rectangular compartment between said endcompartments, said third compartment having a. cross-sectional areaapproximately two-thirds that of said inlet, said partitions beingarranged to provide rectangular openings between said end compartmentsand saidthird compartment remote from said inlet and said outlet, abaffle in said third compartment extending transversely between saidpartitions for preventing direct passage of air from one of saidopenings to the other and dividing said third compartment into twosections having an opening therebetween whereby air passing from saidinlet to said outlet is directed through said compartments in atortuousA path, all of said openings being of sub stantiallyythe samesize and each having an area substantially one-third the area of saidinlet.

HARRY A. WHITESEL.

